IWG RD-ASEP is developing a mandatory test to assess compliance with paragraph 6.2.3 of Regulation 51.04 main body, assuring vehicle noise emission at speed, load, or acceleration conditions other than Annex 3 condition is linked to vehicle physics with no noise emission test detection or defeat device schemes. After the 13th session in June 2026, the Editing Task Force created a consolidated R51.04 draft incorporating R51.03 Supplements up to Supplement 11, with mandatory random RD-ASEP testing for approval and revised control range. Submission targets include informal document first draft September 2026, second draft February 2027, and expected working document for adoption February 2028.

Japan comments on the draft 04 series of amendments to UN R51 (Noise of M₁–M₃ and N₁–N₃ Categories of Vehicles). Japan highlights several editorial and technical issues. Regarding para. 2.24.1, Japan suggests the table of symbols for Annex 3 should state symbols are “used for the first time” consistent with ISO standards. For para. 3.1.2.1.4.3, Japan requests deletion of “but no more than 2.0 m/s²” as unnecessary for RD-ASEP applied to electric vehicles. Japan notes para. 6.2.3.4 should reference appropriate appendices for the RD-ASEP statement of compliance requirement. Paragraphs 11.1.4 and 11.1.5 are identical and one should be deleted. Japan flags para. 3.2.3.4.2 requires tyre conditioning on outdoor test tracks for indoor testing. For Annex 6, para. 3 should clarify that compliance assessment references para. 5 of Annex 7 for expected sound pressure level limits applicable to conformity of production testing.

The IWG RD-ASEP informal group is developing a mandatory procedure for UN R51 after the monitoring phase. The Analysis Task Force determined vehicle databases and expectation models are suitable for RD-ASEP development. The Editing Task Force created a consolidated R51.04 draft submitted to GRBP-84. The revised R51.04 RD-ASEP includes manipulation and defeat device provisions, mandatory random testing for approval, revised control range, any acceleration position testing, vehicle speed range 0-100 km/hr, and vehicle performance criteria. A revised companion document GRB-68-03 is necessary.

Proposal to add, modify, and amend Annex 3, Annex 4, Annex 5, Annex 6, Annex 7, Annex 8, Annex 9, and Annex 10, insert Annex 9 (Measurement method to evaluate compliance with the Real Driving Additional Sound Emission Provisions (RD-ASEP)), and add provisions concerning sound emissions, test methods, measurement instruments, vehicle specifications, conformity of production, exhaust systems, compressed air noise, indoor testing, and specific provisions for vehicles equipped with an Automated Driving System (ADS).

Proposal to add, modify, and amend Annex 3, Annex 4, Annex 5, Annex 6, Annex 7, Annex 8, Annex 9, and Annex 10, insert Annex 9 (Measurement method to evaluate compliance with the Real Driving Additional Sound Emission Provisions (RD-ASEP)), and add provisions concerning sound emissions, test methods, measurement instruments, vehicle specifications, conformity of production, exhaust systems, compressed air noise, indoor testing, and specific provisions for vehicles equipped with an Automated Driving System (ADS).